Patent GB-270446-A (GB)
Title: Manufacture of new azo dyes suitable for dyeing regenerated cellulose silk
IPC: C09B33/10
Filed: 1926-02-24
Abstract: 270,446. British Dyestufts Corporation, Ltd., Baddiley, J., Chorley, P., and Brightman, R. Feb. 24, 1926. Azo dyes dyeing regenerated cellulose silks, e.g. viscose silk, in level shades are made by coupling diazo compounds, excepting those made from aminonaphthols and their derivatives, with 8: 8'-dihydroxy-2 : 2<1>-dinaphthylamine-6: 6' - disulphonic acid or 8: 8<1>-dihydroxy-2 : 2'-dinaphthylamine-3 : 6: 3<1> : 6<1>-tetrasulphanic acid. In examples (1) m-aminobenzoic acid (2 mols.) is diazotized and coupled in alkaline solution with the disulphonic acid; the product dyes viscose silk a brown shade; alpha-naphthylamine, p-chloraniline, and m-xylidine may also be used as diazo components, or diazo components containing nitro or acylamino groups may be used, the products being reduced or hydrolyzed to yield dyestuffs which can be diazotized on the fibre and developed, e.g. the dyestuff obtained on hydrolysis of the product from p-aminoacetanilide (2 mols.) and the disulphonic acid dyes viscose silk a violet-black which changes to blue when diazotized on the fibre and developed with #-naphthol; (2) aminosalicylic acid obtained by reducing the technical mixture of nitrosalicvlic acids is diazotized and coupled with a-r.aphthylamine; the resulting aminoazo compound (2 mols.) is again diazotized and coupled in alkaline solution with the disulphonic acid; the product dyes viscose silk bluish-black, while the corresponding dyestuff from aminoazobenzene sulphonic acid gives a deep brown; (3) dehydrothio-p-toluidins sulphonic acid (2 mols.) is coupled in alkaline solution with the tetrasulphonic acid, the product dyes viscose silk a maroon shade, the corresponding dyestuff from aniline giving a red shade; if nitro or acylamino groups are present in the diazo compound they may be reduced or hydrolyzed in the product and the resulting dyestuffs may then be diazotized on the fibre and devedoped, e.g. if paminoacetanilide is used as diazo component, the hydrolyzed product dyes viscose silk bluish-violet, which changes to brown when diazotized and developed with m-toluylenediamine; (4) p-aminoacetanilide (2 mols.) is coupled in alkaline solution with the tetrasulphonic acid, the product is hydrolyzed, again diazotized and coupled with #-naphthol (2 mols.), the resulting dyestuff gives navy blue shades on viscose silk; (5) m-nitraniline (2 mols.) is coupled with the tetrasulphonic acid, the product is reduced, rediazotized and coupled with H-acid (2 mols.), the resulting dyestuff gives violet shades on viscose silk; (6) mxylidine sulphonic acid (Me: Me : NH2 : SO3H= 1 : 3: 4 : 5) is diazotized and coupled with mamino-p-cresolmethylether, and the resulting aminoazo compound (2 mols.) is coupled with the tetrasulphonic acid; the product dyes viscose silk navy blue, whereas the corresponding dyestuff from salicylic-azo-alpha-naphthylamine gives a blueblack; (7) the tetrasulphonic acid is coupled with diazotized p-nitraniline -o-sulphonic acid in acid solution and with diazotized alpha-naphthylamine in alkaline solution: the product dyes viscose silk a violet shade; (8) the disulphonic acid is coupled with diazotized naphthionic acid in acid solution and with diazotized o-anisidine in alkaline solution, the product gives a violet--brown shade; (9) p-nitraniline (1 mol.) is diazotized and coupled with the disulphonic acid, the product dyes viscose silk a greenish-grey which changes to brown when developed on the fibre with diazotized pnitraniline; (10) p-nitraniline (2 mols.) is diazotized and coupled with the disulphonic acid ; the product dyes viscose silk in grey shades which can be modified by development, on the fibre with diazo compounds; (11) diazotized p-nitraniline (1 mol.) is coupled in acid solution with the disulphonic acid, and the product is coupled in alkaline solution with diazobenzene (2 mols.), the resulting dyestuff dyes viscose silk reddish brown; and (12) diazotized p-chloraniline (1 mol.) is coupled with the disulphonic acid in weak acid solution; the product dyes viscose silk a brown shade which can be modified by development with diazo compounds. In an example of dyeing on regenerated cellulose silk, the dyebath is made up with Glauber's salt, soap and the dyestuff described in the first example; other salts or dyeing assistants, e.g. borax or sodium carbonate may also be added. One of the Provisional Specifications gives further examples of dyestuffs, in which the tetrasulphonic acid is coupled with diazotized dehydrothio-p-toluidine sulphonic acid (1 mol.), or with o-anisidine (alkaline) and dehydrothio-p-toluidine sulphonic acid (acid); the products give maroon shades on viscose silk. 8 : 8<1> - dihydroxy-2: : 2<1>-dinaphthylamine-3 : 6 : 3<1> : 6'-tetrasulphonic acid is obtained by boiling 2: 8-aminonaphthol-3 : 6-disulphonic acid with sodium bisulphite liquor, the product being salted out and freed from sulphite by stirring with dilute hydrochloric acid.